Z axis inconsistent movement

Hi all.

I have a weird problem with my 100 watt chinese blue and white laser 2017 model. For some reason the z axis movements never stay consistent. This has been going on since the day i first got it 6 months ago. I can cut through 3mm plywood at 15% on certain areas of the bed but it wont go though in other areas even if i take the power up. It does this no matter what would i use. Ive spent lots trying to solve this issue with no success. Even after removing the honeycomb and z axis steppers the levelling the bed to the gantry using a spirit level and feeler gauges i still have the same problem… as soon as i use it the bed is uneven again. Can anyone help b4 i go totally grey ir turn it into a 6g workbench.

It’s relatively an old laser. I’d suggest you check the output of the tube for it’s state. If it’s operating in TEM0 mode then you have an alignment issue, optical or mechanical.

Since it’s ‘never worked’ it’s difficult except to start at the basics.

If the carriage is not level, leveling the bed will not help. Distance from laser lens to the bed is the key, not if it’s level or not.

Post a photo of the beam at m1 coming out of the tube.

Good luck


Not knowing precisely how the Z-axis works leaves me with a couple of questions and ideas.

I’d like to confirm that the Z axis is driven by 4 vertical Acme-type lead screws connected to the drive motor by one long continuous belt.

The problem with a 4 legged bar stool is that it’s over-constrained. It takes three points to define a plane and a fourth one to define a second plane and the intersection line the system (bar stool) rotates around. If any one of the 8 rod ends isn’t constrained the engraver bed may be bouncing between two planes. Grab a corner and lift up and push down. See if you can feel end-play in one of the lead screw assemblies.

Listen carefully for oil-canning as the bottom of the cabinet may be stretched and springing from one position to another.

How large was the error you previously observed?

I look forward to seeing this riddle resolved. :slight_smile:

Sorry, but for some reason im not getting notifications of replies from the forum. Only noticed your reply as i was browsing. Anyways… i still have this issue, there are four posts on the z axis table that are run by 2 separate belts and stepper motors. After getting it perfectly level and raising and lowering it the gap in one corner was 3mm lower, its one of the reasons y im having trouble cutting in some areas of the bed. The other reasons are never buy a laser from Roger Webb.

I took the liberty of removing the indent (code) window from your reply.

You’ve got a couple of solid suggestions as to what might be going on.
Please report back after you’ve attempted some of the diagnostics.
It may help others with their purchases.